Distribution of Densities within Metropolitan Cities: The Case Of Greater Region

Dr. Ghada Farouk Hassan Dr. Mohamed A. Salheen

ASSOCIATE PROFESSOR - URBAN PLANNING DEPT. ASSOCIATE PROFESSOR - URBAN PLANNING DEPT. FACULTY OF ENGINEERING - UNIVERSITY FACULTY OF ENGINEERING - AIN SHAMS UNIVERSITY 1 EL-SARAYAT STREET, CAIRO, . 1 EL-SARAYAT STREET, CAIRO, EGYPT.

[email protected] [email protected] Abstract

Population density is one key factor in describing how cities live, operate and develop. Its dis- tribution and change over time can be one of the most revealing aspects of its attributes. This paper analyzes the distribution of densities in the main agglomeration of Cairo, which is some- how a specific case in the physical development and growth of a city. Cairo developed until the early 19th century around its original city boundaries, but starting from then it followed a clear- ly different approach by having piecemeal additions that are not necessarily adjacent to the ex- isting agglomeration. This was followed by various flows of migration and attack.

The paper aims to attain a better understanding of the city development. It does so by reviewing different models of Distribution of Density in Cities. It then moves to further exploring the spe- cific Factors affecting densities changes and population movement from the inner city in the Metropolitans. These two sections aim at drawing on previous experience and theories of popu- lation change in other contexts and cities.

The paper then presents the analysis of densities in Cairo, physically divided into 23 zones linked to the population database. It starts with a Descriptive analysis of the chronological change of zone density. Then it illustrates the Spatial Disruption of Densities on the years from 1976, 1986, 1996 and 2006 when the last consensus was conducted.

Then it presents the findings of the Cluster analysis of District densities which helped in draw- ing conclusions and understanding the common attributes of the different districts and the im- pact of the different factors on the density of each district. Finally the Cluster Analysis of Change in Density Rates is discussed which gives more insight on the impact of different fac- tors on the development of population density of different districts over time.

The paper finally concludes with the main findings of the review and analysis giving insights on the factors affecting the population density in different parts of the city and its relation to various urban, social and economic attributes. It further recommends on specific areas of re- search that requires more exploration in order to understand the situation in Cairo more. Specif- ic recommendations for Cairo future plans are also being proposed as a trial from this paper to contribute to the development of Cairo 2050 plans for the Region.

Keywords: population movement, density distribution, city development, Cairo.

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1. Introduction

Greater Cairo Region, Egypt (including governorates of Cairo, Giza, Qaliobeya, and 6 of October) is well known for its high-density form of development. The main urban agglomeration of the Cairo Metropolitan city is 521 km2, and its average density is 397 persons/Hectare (World Urban Forum 2010). The annual urban growth rate of the main GCR is 3.7%. Many development plans since 1982 has been proposed to build new communities and cities around the capital that was defined by a ring road. From such proposals a common idea of laminating growth of the capital and adding new urban corridors in the east and the west is dominating.

A strategic plan for Cairo 2050 is currently prepared. Many projects to improve econ- omy and investments and to enhance transportation are proposed, in order to realize the new strategy that main concept is the Redistribution of population within the region Limiting further residential units in the Capital and opening new access roads, and providing new residential zones within the Region.

Accordingly, it is important to understand the way the Cairo metropolitan city operates and identify factors affecting the change in density from one place in the city to the other over time and with specific reference to its location within the city. The complex economic and so- cial relations that gave rise to the emergence of large cities produce a physical outcome – the urban built-up space – which can be mapped and measured. This paper will help in reaching more realistic impacts of each actions/projects proposed to contribute in the new strategy of Cairo.

The recently developed technologies such as satellite imagery, digital mapping and ge- ographical information systems make it possible to have a much better knowledge of the urban shape than was the case in the past. At the same time, monitoring and managing the spatial ex- pansion is much more complex than what it used to be.

2. Distribution of Densities in Cities

Urban structure is the arrangement of land use in urban areas. Sociologists, economists, and geographers have developed several models, explaining where different types of people and businesses end to exist within the urban setting. Various theories focusing on the distribu- tion of densities within cities are presented and discussed. The Monocentric model assumes that there is one mode of transportation and the cost per unit distance is constant. Smith [14] conclude that density gradients have flattened for a large number of countries over long time periods, and are higher in the CBD than on the city boundary as conclud by Rodwin, L. [15]

Moreover, the 1970s and 1980s have seen the formation of "Edge Cities" as described by Mills, Edwin S. [12] and clarified by Garreau [7]. These cities are to be understood as col- lections of employment and surrounding residential areas which are located in the suburbs- often distant suburbs-of large urban areas. The explanations of variations in the density gradient among metropolitan areas were not successful in determining the relative importance of the natural evolution and the "flight from blight" explanations of suburbanization.

Hoyt [11] in his model, published in 1939, attempts to state a broad principle of urban organization. He theorized that cities tend to grow in wedge-shaped patterns – or sectors – emanating from the central business district and centered on major transportation routes. Resi- dential functions would grow in wedge-shaped patterns with a sector of low-income housing bordering manufacturing/industrial sectors (traffic, noise, and pollution makes these areas the least desirable) while sectors of middle- and high-income households were located furthest away from these functions. This occurred in Calgary in the 1930s when many near-slums were 2

established outside the city but close to the termini of the street car lines. These are now incor- porated into the city boundary but are pockets of low cost housing in medium cost areas. Carter [6]

Following Hoyt development model, Harris and Ullman [10] introduced the Polycen- tric Model which is more effective generalization of urban land uses large cities do not grow around one CBD, but are formed by the progressive integration of a number of separate nuclei in the urban pattern. These nodes become specialized and differentiated in the growth process.

Trip pattern will therefore depend on the relative location of residences and meeting places within the metropolitan area. In a Monocentric city the location of the majority of these meeting places is heavily concentrated in a central area. In a polycentric city, the majority of the meeting places are distributed in clusters around the metropolitan areas. Therefore, polycen- tric cities have a negatively sloped density gradient, not necessarily cen- tered on the CBD but on the geomet- ric center of gravity of the urbanized area. The slope of the gradient should be flatter, as the proximity to the center of gravity confers an ac- cessibility advantage that is not as large as in a Monocentric city. The existence of a flatter but negatively sloped density gradient in Polycen- tric cities can be observed in cities that are obviously polycentric.

“No city is ever 100% Monocentric, and it is seldom 100% Polycentric (i.e. with no discernable “downtown” Bertaud, Alain [4]

Some cities are dominantly

Monocentric, others dominantly Pol- FIGURE 1 SHOWS MODELS OF CITIES STRUC- ycentric and many are in between. TURE Some circumstances tend to acceler- ate the mutation toward poly-centricity – historical business center with low level of amenities, high private car ownership, cheap land, flat topography, grid street design –; others tend to re- tard it – historical center with high level of amenities, rail based public transport, radial primary road network, and difficult topography preventing communication between suburbs.

3. Movements from Inner City towards Peripheries

The "natural evolution theory" happens while the land in the central city becomes filled in, development moves to open tracts of land in the suburbs on the peripheries. When the cost of moving goods and people within cities was high, and urban areas were dense. Then, small, high income groups located at the center moved to the periphery. The older, smaller housing units, which were centrally located, were left down to lower income groups. This natu- ral working of the housing market leads to income stratified neighborhoods, and there is a ten- dency for low income groups to live in central locations and for affluent households to reside in outlying suburban areas. The tendency of the middle class to live in the suburbs has been rein- forced by transportation innovations and travel time considerations. This theory is also ensured by the growth of urban sprawl as takled by Brueckner, J. and Hyun-A Kim [5]

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In contrast, "The flight from blight theory" Isaac Bayoh [3] stresses fiscal and social problems of inner cities: high taxes, low quality public schools and other government services, racial tensions, crime, congestion and low environmental quality. These problems lead affluent central city residents to migrate to the suburbs, which leads to a further deterioration of the quality of life and the fiscal situation of central areas, which induces further outmigration.

The two theories have a number of interactions and interrelations, Peter Mieszkowski and Edwin S. Mills [13] and consequently, it is difficult to distinguish between them empirical- ly. For example, the "flight from blight" theory implies that important externalities are involved between income groups: positive externalities from the affluent to the poor, and negative exter- nalities running the other way. But the other theory based on income changes and is technolo- gy, consistent with the same externalities.'

The population movement within the city can be a result of the Improvements in transportation and telecommunications. The urban land use pattern thus tends to be far less coherent, more specialized and dispersed.

In addition, movements follow Activi- ties that have spatial locations creating a land use pattern, which is influenced by the existing urban form and spatial structure. This form is strongly related to the types of activities that can roughly be divided in three major classes: SOURCE: GARREAU, JOEL, (1991) ADAPTED • Routine Activities. This class of activities is occurring regularly and is thus predictable. FIGURE 2: URBAN PATTERN FOLLOWING They involve journey to work (residential to industrial / commercial / administrative) and shopping (residential to retailing). • Institutional Activities. Most institutions are located at specific points and generally have links with individuals (Students, sports, leisure, etc.) or special needs (health). • Production Activities. This involves a complex network of relationships between firms, such as control, distribution, warehousing and sub-contracting.

Some activities are strongly linked to the local urban area, while others are far more linked to the global economy as Rod Burgess [2]. The land use pattern of an activity may thus be linked to an external (international) process. These activity systems underline the importance of linkages between land uses, which require movements of people, freight and information.

4. Factor Affecting Densities Changes

4.1 Density versus Land Value

According to Bertaud [4] the Cities urban structures have been shaped by economic forces, they have been very seldom the result of design. As the raison of being large cities is the size of their labor and consumer markets

The land economics are concerned about how the price of urban land is fixed and how this price will influence the nature, pattern and distribution of land uses. ther is some basic rela- tionships between the quantity of land and its price. This mechanism follows the standard mar- ket relationship between supply and demand, where an equilibrium price is reached.

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Obviously, not every type of activities is willing to pay a price P1. Some may even need a price lower than P3. High land values impose a more intensive usage of space so the highest number of activities can benefit from a central location. The logic behind the construc- tion of skyscrapers is therefore obvious and takes place at optimal locations of competition for land.

Value of Land use is determined by the rent-paying ability of different economic functions in urban areas, such as retailing, industry and residence. The optimal loca- tion, where accessibility is optimal, is the central business district. Density and land value are closely related. Bertaud [4] had concluded that the downtown area is not necessarily the most accessible location. The rapid extension of metropolitan areas in- volves new locations far from the CBD, no- tably in suburbia (E). This has favored the FIGURE 3 DIRECT RELATION BETWEEN emergence of sub-centers (D) having a con- LAND VALUE AND DENSITIES CHANGES, centration of retailing, commercial, distribu- PARIS METROPOLITAN CITY. BERTAUD tion and industrial activities, mainly aimed at [4] servicing a growing population. A signifi- cant share of the land, notably nearby central areas, is captured and not available on the real estate markets. Governments, institutions, parks, industries and transport infrastructures occupy a large part of most central areas and this ownership can last for several decades (if not several centuries for historical landmarks). This caused an imbalance in the price fixing mechanism in central areas with less land available (thus higher prices) that has favored urban sprawl.

Bertaud [4] presented graphically spatial distribution of the population by combining census data and land use maps to construct a 3 dimensional object where the map of the built- up area is in the XY plane and the population density within the built-up area is shown in the Z dimension.

As C. C. Acioly, Jr. and F. Davidson [1], the center of gravity will be the point to which the average distance per person is the shortest. He also identified on this 3 dimensional object special areas of the city like for instance its central business district (CBD and then cal- culate what is the average distance per person to the CBD and whether the CBD and center of gravity coincide.

Figure (3) shows the spatial distribution of the population of Paris metropolitan. The profile of densities is the key to understanding a city’s structure and its livability and Cities where the land market works reasonably well have a common structure.

4.2 Densities vs. Land Use Regulations, Poverty & Metropolitan Struc- ture

Bertaud [4] cited that Land-use regulations have 2 contradictory effects on densities and land price: "(1) direct effect is to decrease densities and land price: minimum lot size, maximum floor area ratio, minimum road width; all contribute to a decrease of densities and price. (2) But an indirect effect of regulations could increase densities: some regulations might decrease the supply of land, therefore pushing land price up and as a consequence densities."

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He concluded that: (1) Land is always affordable to all income groups. Different in- come group will adjust their consumption of land (and therefore density). (2)Land use regula- tions always implies establishing maximum density thresholds in specific locations, these thresholds are typically lower than the one reached by an unregulated market.

Land use regulations, when not enforced, fragment land markets into two sectors: the formal and the informal market. According to UN-HABITAT 2009 [17] and UN-Habitat, 2010 [18] poor households pushed by regulations into the informal market loose the normal contrac- tual guarantees given by the State to its citizens. As a consequence, they have to pay more for land and infrastructure for a lower level of service, and they do not have access to the formal financial markets.

4.3 Factors Affecting Densities Changes & Movements in Metropolitans

It can be concluded from the literature review done previously that main factor affect- ing densities and it distribution in the city are as shown in the following table:

Natural growth (While the land in the central city (first area to be built) becomes filled in, development moves to open tracts of land in the suburbs on the peripheries. Therefore it can be concluded from the above discussion that many factors are affecting population distri- bution and the densities changes in metropolitan cities from following the natural growth theo- ry: Social problem and income group displacement of inner cities ("the flight from blight" theories) cause the decline in densities of the inner city. Land values (Moving towards the downtown the demand rises, land becomes scarcer and the price goes up but the rapid extension of metropolitan areas involves new locations far from the CBD that caused the movement towards the periphery, where more land is available, the prices drops. Planning status and regulations, (some regulations might decrease the supply of land, therefore pushing land price up and as a consequence densities). By consequences can segre- gate market by formal and informal. Population densities in informal markets are higher and costs of dwelling are more affordable for low income groups than population densities in for- mal market where land have regulations for planning or building. Transportation and activities distribution: a strong and direct relationship between densities changes and transportation improvement or activity location

The following table is summarizing main findings as derived from previous sections:

Factors affecting densities Social stratum Planning status Land value transportation Activities

Effects indirect indirect direct direct direct

TABLE 1 FACTORS AFFECTING DENSITIES IN CITIES Source: The authors

5. Analysis of Densities in Greater Cairo Region (GCR)

5.1 Spatial Disruption of Densities:

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According to the result of Urban Survey 2007 [16] for the main agglomeration of Greater Cairo Region (GCR) done in the favor of Cairo 2050 project and declared at GOPP publication 2009, the research traced the development of population density in all Shiakhas1 of GCR (smallest administrative boundary which is a subdivision of the direct level) over the four census records available for the years 1976, 1986, 1996 and 2006. The last was used to project a predictive population density for 2010 using historical records, and this is shown in figures (4, 5, 6 and 7)

FIGURE 1: DENSITY DISTRIBUTION IN FIGURE 2: DENSITY DISTRIBUTION IN CAIRO 1976 CAIRO 1986

FIGURE 3: DENSITY DISTRIBUTION IN FIGURE 4: DENSITY DISTRIBUTION IN CAIRO 1996 CAIRO 2010 Source: The Authors

1 Shiakha is the smallest administrative boundary which is a subdivision of the direct level. 7

By describing densities changes from the year 1976 to 2010, two major movements can be identified as follows:

The first movement was between the periods of 1976 to 1986. It was the movement of the population from the CBD to the surrounding area. This phenomena, is explained by the nat- ural growth in section 2 and applied in the Cairo case. Cairo city tended to grow in wedge- shaped patterns emanating from the central business district and centered on major transporta- tion routes from the north to south and from the CBD to the west going to the pyramids of Giza. This phenomenon was limited by the existing of natural feature i.e. The MOKATAM hill in the east and the agricultural land in the west.

The second movement was happened within the last 20 years, where the downtown ar- ea is not necessarily to most accessible location. The rapid extension of Cairo metropolitan are- as involves new locations far from the CBD. This has favored the emergence of sub-centers having a concentration of retailing and commercial activities, mainly aimed at servicing the growing informal settlements on the peripheries the natural growth as shown in the figures.

5.2 Descriptive Analysis of District Densities:

In this analysis and the following ones the research worked on a higher geographical level which is the homogenous zones developed within the Cairo 2050 plan as seen in the fig- ure 13. This will help in avoiding possible bias due to the granularity of the Shiakha level which might also result from errors resulting from census surveys. Working at this level will also help to understand the situation of these homogenous zones better so as to support the ef- forts of Cairo 2050 and to benefit from the wealth of information developed within this study which is the most updated and comprehensive.

400

350

300

250

200

150

100

50

0 Zone 7 Zone 9 Zone 6 Zone 2 Zone 8 Zone 1 Zone 4 Zone 5 Zone 3 Zone Zone 17 Zone 15 Zone 16 Zone 12 Zone 21 Zone 18 Zone 11 Zone 19 Zone 23 Zone 13 Zone 10 Zone 22 Zone 14 Zone 20 Zone

Z. Den_09 Z. Den_06 Z. Den_96 Z. Den_86 Z. Den_76

FIGURE 8: ANALYSIS OF POPULATION DENSITIES PER ZONES SET BY GOPP Source: The Authors 2010

This was done by Sorting the population density of the 23 zones ascending according to 2009 densities and then checking the chronological change of each zone on the four time points of 1976, 1986, 1996 and 2006. This shows the following observations:

Highest population density rates exit in 20-, 3-Ain Shams, 14-Dar El-Salam, and 5-El- Waily respectively. Despite the fact that they are all popular areas, only the latest is historically dense zone and the other three they gained most of their density within the twenty years 1976- 1996. Other districts like 22-Haram, 4-Shobra El-Khaima, 1-Marg, and 23-Omrania are signifi-

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cantly increasing their density, yet with tendency to continue increasing as the rate of increase does not change in 1996 but rather significantly increased between 1996 and 2006.

On the other hand very few zones which experienced decrease in population density especially if a continuous decrease is considered. Only three are worth mentioning and these are 13-, 12-Downtown and 11-Daher & Abbasia. These are the central districts of Cairo and which points clearly to the tendency of these districts to accommodate more business uses over their historic and existing residential uses. Finally it was noted that there are several zones with significantly low population density but this is due to the inclusion of wide areas of expansion opportunities and which are also planned but not fully developed and populated such as 15 May, West NC, , Eastern Expansion desert and Helwan.

5.3 Cluster Analysis of District Densities:

In this analysis the density of the 23 zones over the four time periods 1976-2006 and 2009 pro- jection were analyzed using SPSS. The analysis relied on testing the hierarchical Cluster analy- sis using Average Linkage (Within Groups) method and the measure is the simple Euclidian Distance. The resulting clustering of the zones of Cairo shows some interesting outcomes.

G1 G11

G9

G2

G3

G4

G5

G6

G7 G10

G8

FIGURE 9: ANALYSIS THE DENSITY OF THE 23 ZONES OVER THE FOUR TIME PERIODS 1976-2006 AND 2010

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Zone characteristics:

The four main characteristics of each zone which are initially assumed to have an im- pact on the development of zone density are: social class, land use, location, and planning histo- ry. Social Class is defined as the prevailing (over 50% of the full population) economic level of residents which is divided into (low; middle and High). Land Use is the prevailing (around 25% for non-residential) land use character and was found to be one of Six types [residential; formal business; tourism/historical; mixed use; industrial/residential; and informal busi- ness/residential]. Location could be one of three central, peripheral or intermediate. Finally the Planning History is a character which describes the initiative behind the establishment of each zone.

This was found to be one of four categories Historic (until 1867); Informal (following 1952); Modern (governmentally planned after 1867) and Transitional (1867-1952) and the lat- est are areas that were self developed between central and peripherally planned areas but fol- lowing systematic planning rules and regulations. This is because Cairo did not follow a circu- lar expansion but rather a distant patchy form of additions which resulted in massive undevel- oped intermediate areas that were left to experience various forces of pressure and tension that shaped its .

Clustering Level Zone Characteristics Z. # Zone Name Location Planning 3 2 1 Social stratum Activities from CBD Status 8 Manshiet Nasser & Graveyards Low Inf. Bus./Res. Intermediate Informal 21 Faisal Middle Inf. Bus./Res. Peripheral Transitional G1 Industrial 16 Helwan Middle to low Peripheral Early planned /Residential 6 Heliopolis & Eastern NC Middle to high Formal Business Peripheral Early planned G9 9 Eastern Desert Middle Residential Peripheral Newly planned G11 15 Maadi High Mixed use Peripheral Early planned G2 17 15th of May low Residential Peripheral Newly planned 7 Western NC Low Residential Intermediate Newly planned Industrial/ Resi- 2 El-salam Low Peripheral Informal dential 23 El-Omrania Low Residential Peripheral Informal G3 1 El-marg Low Residential Peripheral Informal 11 El-Daher & El-Abbasia Middle Formal Business Central Historic 12 Downtown Middle to high Formal Business Central Historic G4 Tour- 18 Nile Water Front High Central Informal ism/Historical 19 Mohandeseen & Giza High Formal Business Central Early planned 10 Shobra Middle to low Mixed use Central Historic Tour- 13 Old Cairo Middle to low Central Historic G5 ism/Historical Industrial/ Resi- 5 El-Waily Low Central Transitional dential 14 Dar El-salam Low Residential Intermediate Informal G6 3 Ain Shams Middle to low Residential Intermediate Transitional Industrial/ Resi- G10 4 Shobra El-Khaima Low Peripheral Informal dential G7 Industrial/ Resi- 22 El-Haram Middle Peripheral Transitional dential G8 20 Imbaba Low Residential Peripheral Informal

TABLE 2 REPRESENT THE ANALYSIS OF ZONE CLUSTERS OF SIMILAR DENSITIES IN CAIRO METROPOLITAN VERSUS SOCIAL STRATUM, ACTIVITIES, LOCATION AND PLANNING STATUS Transitional: unplanned but upgraded area that was initially informal Historic: area planned before 50s Early planned: area planned from 50s to 70s Newly planned: area planned after 70s

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The analysis above shows that the main attribute which leads to differentiation and de- velopment of the zone density is its location as it is quite significant that the groups and sub- groups which resulted from the cluster analysis of the 23 zones and their density development since 1976 till current days. Social class on the other hand did not show any significant consist- ence with the group formation and division.

5.4 Cluster Analysis of Change in Density Rates:

In this analysis the study traces the possible clustering of Zones of Cairo based on the change in the rate of change in their population density. This takes the analysis a step further by investigating the attractiveness/repulsiveness levels of each zone. This clustering reveals even more four distinct groups of Cairo districts.

1) Central zones: these are the areas that have been experiencing a continuous de- crease in their density. This decrease is the result of the migration of the residents of the central areas such as Downtown, Old Cairo, Daher & Abbasia for the favor of increase in business uses. Others are in this group for having reached a high lev- el of saturation during the late seventies/early eighties when the first census was conducted on 1976. These districts are Shobra, Waily, Mohandeseen & Giza and finally the Nile front.

2) Saturated zones: these are informal areas that have started 30-40 years ago but cur- rently have reached a high level of density that it cannot increase significantly any more. The areas in this group are Faisal, Imbaba and finally many informal areas such as Haggana which is located in Heliopolis & East (early planned zone).

FIGURE 10: CLUSTERING OF ZONES OF CAIRO BASED ON THE CHANGE IN THE RATE OF CHANGE IN THEIR POPULATION DENSITY Source: The authors

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3) Inner zones: These are the transitional and the early planned areas which emerged on the edge of the city (at one point of time) but now are inner areas given the mas- sive expansion of the city beyond their limits. These areas are still experiencing densification with additional floors or the complete replacement of short buildings with others which can reach the maximum height possible. These are Helwan, Ha- ram, Manshiet Nasser and Ain Shams.

4) The peripheral zones: These are zones which include transitional and early planned areas that still not completely enclosed with mature expansion of the city. These ar- eas are experiencing horizontal expansion on its surroundings. These are shobra Khaima, West Nasr City, Omrania, Dar Elsalam, Marg, Maadi and Eastern Desert areas.

5.5 City Sections:

A 3D model was built for all Shiakhas in Cairo and from this model various sections were developed. Among these sections the following three sections were found more representative and revealing for the forces shaping the density of different areas of the city based on their lo- cation within the city as well as other interpreting aspects.

• Section A-A runs South-East to North-West. It crosses the Nile passing through Island.

• Section B-B Runs North South with an angle passing through Port Said Street which is the longest vertically running straight street in Cairo.

• Section C-C runs North-East to South-West. It crosses the Nile through Manial street and B

C A

C A

B

FIGURE 11: CITY SECTIONS SHOWING DITRIBUTION OF DENSITIES 12

goes further West through Haram Axis leading to the Pyramids.

Section A-A B C

Section B-B C A

Section C-C B A

FIGURE5 DISTRIBUTION OF DENSITIRES IN CAIRO SHOWN BY SECTIONS

6. CONCLUSION

The paper concludes through the analysis done and the understanding of the Cairo Met- ropolitan with the following:

Tracking the distribution of densities in Cairo Metropolitan Area over time reveals its dynamic change. Density decline changes reflect the death of the main CBD, but at the same time its significant increase in other peripheral areas point to the emergence of new sub centers at the edge of the agglomeration. This is a commonly acknowledged pattern in modern metropolitans. This in turn opens the chance to build analogies with future changes at both the inner city and the outer areas comparing to similar cases. This kind of city development was revealed in city sections AA and CC, and can be explained by the theories of natural evolution theory. There-

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fore, the CBD of Cairo is not only an old center of a metropolitan city; but also, it contains many historical, esthetic, and social aspects. So this natural phenomenon cannot be over looked without an action to control this decline, and also reuse such zone.

Informal zones which are initially zones without regulations were easily identified as they have reached a high level of density. The tendency of the population to concentrate in these areas can be justified by the lack of land use regulations, thus the low value of land, and the agglomera- tion of lower income groups to live there. This phenomenon is explained by the theory of Ber- taud 2001, and can be applied in Cairo case study. However, lately this explanation that could be valid till the 90s, is no longer valid, till 2010.

The emergence of significant and overwhelming increase of the density of zones located in the north-south direction, as shown in section BB, is tracked and has shown their tendency to con- tinue increasing as the rate of increase does not change in 1996 but rather significantly in- creased between 1996 till 2010. This movement cannot be explained by the natural evolution anymore (i.e. no emergence of new centers) but the linear shape of change can be justified by the construction of the underground Metro line that easily links the peripheries to the downtown with the same cost even if the distance is longer. This fact directs planner to rethink the location of new planned metro lines: to really realize the objective of easily link with- Metro line 1 Metro line 2 out causing new problems of densities and overconcentration.

When informal zones in the inner city reached their maximum capacity and became saturated, other peripheral zones experienced vertical and/or hori- zontal expansion on its surroundings and are forming new informal pockets. This shows that the process of infor- mality in Cairo is a continuous process that is initially led by suitable physical location and urban context, but also goes beyond that to other less attractive and suitable locations. Controlling this process should deal with the routes and causes for the process and not its im- mediate and apparent symptoms shown at existing informal areas.

Although the state exerted many efforts to decrease densities by upgrading in- formal zones and/or by developing new FIGURE6 : CAIRO EXISTING UNDERGROUD METRO planned areas especially in the east, , LINES ONE AND TWO these efforts did not achieve their goals because:

1- The upgrading policy may encourage the successive formation of new informal zones.

2- The development policy of new lands especially in the east does not provide affordable housing for low income group.

Such observation and understanding may direct the decisions taken towards the future of Cairo metropolitan to redistribute population, accordingly to determine suitable actions needed for each zone not only physically, but also socially and economically.

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